This is an application for a developmental grant for an Autism Center of Excellence. The long-term goal of this proposed Autism Center of Excellence is the delineation of the genetic and neurobiological mechanisms underlying specific autistic traits and the application of this information to treatment and outcome studies. The basic assumption of this goal is that there are multiple and heterogeneous genetic and neurobiological mechanisms that contribute to the observed clinical heterogeneity of autistic children and determine the social and language differences observed in the relatives of these children. The short-term goal of this developmental grant application is the establishment of an interactive structure and environment for interested investigators to realize these aims. The proposed list of investigators include child psychiatry, child neurology, psychology, and occupational therapy experts with a broad range of interests spanning basic neuronal mechanisms, genetic epidemiology, clinical syndromes and treatment response. The central theme of the proposed center, using developmental and genetic epidemiological methods to determine the underlying mechanisms for specific autistic deficits, is based on our recent success applying these approaches to the genetics of the core autistic feature of reciprocal social behavior. The long range goal of the proposed center is to extend these approaches to include tests of basic neurobiological mechanisms which might be associated with these characteristics, to investigate if similar mechanisms act in the broader autistic spectrum of disorders and to investigate the contribution of these proposed mechanisms to the prediction of treatment response. During the initial phase of this center we will concentrate on the establishment of an organizational structure to facilitate the development of junior and established investigators as autism researchers and on the creation of an enhanced integration of clinical and educational programs in autism and related disorders. Pilot studies for this developmental period will include extension of instruments developed for children to adult versions to test for extended familial transmission of autistic traits and the piloting of the use of established instruments in a quantitative trait locus (QTL) analysis of the possible involvement of the X chromosome in deficits in reciprocal social behaviors.